Answer to Question #138292 in General Chemistry for Yara

Question

5.015 g sample of a compound that contained carbon, hydrogen, and oxygen was combusted in a carbon-hydrogen analyzer. The combustion produced 7.35 g of carbon dioxide and
2.99 g of water. Determine the empirical formula of the compound.

Answer 1

Let the compound be C_xHyOz

_{equation : CxHyOz + O2 = CO2 +H2O}

_{(5.015). (7.35) (2.99)}

_{mass of C =12g/mol * 7.35/44g/mol= 2.005g}

_{mass of H =2g/mol* 2.99g/18g/mol =0.333}

_{mass of O2 in CxHyOz = 5.015-(2.005+0.333)= 2.678}

_{moles of Carbon = 2.005/12= 0.167}

_{moles of Hydrogen = 0.333/1 = 0.333}

_{moles of oxygen = 2.678/16 = 0.168}

_{divide all by smallest moles value = C(0.500) H(2) O(0.500)}

_{multiply by whole number (2) = C(1) H(2) O(1)}

_{empirical formula =CH2O.}